Building materials, e.g., concrete, brick, marble, are often porous, difficult to clean and subject to practically permanent defacement with graffiti Painted surfaces are likewise difficult to cleanse of graffiti and dirt. Such surfaces can be of a wide variety including plaster, masonry, concrete, metal, the various types of woods, etc., coated with typical commercial paints including the water-based types and the oil-based types such as water-based latices, water-based enamels, the alkyds, the acrylics, the masonry paints, and others. Polymers which can seal or coat such painted or unpainted surfaces are needed to preserve their appearance and integrity and to allow the relatively easy removal of graffiti and dirt. The object of this invention is to describe hydrophilic polymeric systems which can be applied easily to such surfaces without changing their appearance, which will maintain good adhesion to concrete, masonry and paint even when wet, and which can give the above effects.
It has previously been proposed to coat building materials with hydroxyethyl acrylate monomer and polymerize the same in place: see, for example U.S. Pat. No. 2,827,397 to Affleck. It has also been proposed to preform a homopolymer of a hydroxy lower alkyl acrylate or methacrylate or a copolymer thereof with certain copolymerizable monomers including lower alkyl acrylates and methacrylates, e.g., up to hexyl acrylate: see Belgium Pat. No. 780,838 and German Offenlegungsschrift No. P 2211999.9.
Among the problems with the products produced in accordance with the Affleck procedure is lack of extended durability to weathering and to graffiti attacks due to insufficient polymer cure. The procedure in the Belgium patent and the corresponding German Offenlegungsschrift is an improvement over that of Affleck. However, there is a problem in obtaining adequate adhesion to the building material in some cases.